Reusable oxygen and acetylene tanks (hereinafter referred to a "gas supply tanks") are employed in great numbers on construction sites. These tanks provide the fuel for welding and cutting operations periodically necessary for the construction projects. Unfortunately, during the course of such construction projects, many of such tanks mysteriously disappear. To the contractor, the loss of these reusable tanks can represent a substantial financial loss.
There is no simple way to mark the tanks since they are reusable and are exchanged when empty for full tanks.
Also, there is no easy way to distinguish an empty tank from a full tank in appearance and it is necessary to weigh the tanks to determine the amount of remaining gas left therein. This factor makes it difficult to determine if persons removing tanks are removing full or empty tanks from a construction site, unless some means are provided to weigh the tanks.
Normally, these tanks include a removable threaded cap which is screwed on to the top of the tanks, over the valve stem, to protect the valve stem assembly. However, these caps can be removed at will and often are by vandals who subsequently open the valves and vent the contents of the tanks to the atmosphere. With oxygen and acetylene tanks in close proximity, such acts of vandalism can also create a safety hazard.
Many of the above problems can be overcome with the lock cap unit of the instant invention which provides a cap which can be locked over the valve stem assembly that cannot be removed without a key to its locking unit. Further, a contractor can identify its tanks with the lock cap units installed thereon by painting them with special colors or relying on their serial numbers, since these cap units cannot be removed except when the contractor desires to remove a unit with a key. Further, the installation of the lock cap unit makes it difficult for thieves to market gas supply tanks which contain the lock cap unit because it is difficult, if not impossible, to safely remove it from the tank without the key.
Of course, other advantages besides those noted above, such as protection against vandalism, are provided by the novel lock cap unit.
Further, the lock cap unit is not restricted to oxygen and acetyline supply tanks being suitable for LP gas tanks, nitrogen, etc., which have a threaded neck.